Burner for blast furnace stoves



1967 H. SCHURHOFF ETAL- 3,304,983

' URNER FOR BLAST FURNACE STOVES Filed Sept. 10, 1964 JN VEN TORs HEINRICH say/101200;;

their ATTORNEY.

ed tes Pate Filed Sept. 10, 1964, Ser. No. 395,519 4' Claims. (Cl. 158-11) The present invention relates to blast lfurnace stoves in general, and moreparticularly to improvementsin regenerators ofthe type belonging to the classknow'n'as Cowperstoves.

It is an important object of the presentinventi'on to provide anovel burner for blastfurnace stoves v.arid. to construct the burner in sucha wayv that productsof com bustion, issuing from the combustion chamber of the stove, will heat thechecker chamber with exceptionally high uniformity even though the heatingvalueof furnace gases might fluctuate within a rather wide range;

Another object of the invention is to provide a burner of the just outlined characteristics which is constructed and assembled in such a way that the wall structure of the blast furnace stove is protected from localized "overheating so that the stove is not likely to develop cracks and can withstand long periods of use.

A further object of the invention is to provide a burner which maybe readily and rapidly adjusted for use in connection with-different types of gaseous and/or liquid fuels, wherein the shape, propagation and other characteristics of the flame may be adjusted at the will of the operators, and wherein all such parts which undergo maximum wear may be inspected, repaired, cleaned, and/ or replaced with little loss in time.

An additional object of our invention is to provide a blast furnace stove which embodies a burner of the above outlined characteristics.

A concomitant object of the invention is to provide a blast furnace stove of the type generally known as Cowper stove and to construct and assemble .the stove in such a way that combustion of furnace gases and/or other types of fuel is invariably completed before the products of combustion enter the checker chamber in which the combustion products exchange heat with the checkers during the on gas stage of the operation.

Still another object of the invention is to provide the improved burner with simple, inexpensive but highly effective mixing and atomizing devices which insure that the fuel is properly distributed and intimately intermixed with air or oxygen before such mixture enters the combustion chamber of the stove. I

Another object of the invention is to provide the burner with improved agitating or spinning devices which further contribute to better intermixing of fuel and air prior to entry of such mixture into the combustion chamber.

A further object of our invention is to provide the burner with atomizing, mixing and spinning devices which are of simple and rugged construction but can insure highly satisfactory mixing of fuel and air even though their cost is but a small fraction of the cost involved in using conventional carburetors such as are often utilized for mixing fuel with air or for enriching a fuel of low heating value.

Another object of the invention is to provide a blast furnace stove which consumes small quantities of furnace gases.

With the above objects in view, one feature of the present invention resides in the provision of a Cowper stove which comprises an upright tubular combustion chamber and a burner having a wall of heat-resistant material provided at the lower end of the combustion chamber. This Wall is formed with an annulus of up wardly extending channels including air or oxygen-admitting channels which alternate with channels serving to admit furnace gases into the lower zone of the combustion chamber. The burner further comprises one or more substantially vertical supply pipes surrounded by the annulus of channels. and serving to admit into the combustion chamber oil and/or a gaseous fuel whose heating value exceedssubstantially-the heating value of furnace gases. The heat generated'by burning fuel constitutes the .major part of heat energy necessary to heat the chequer chamber of the stove so that eventual fluctuations in the heating value of furnace gases will have lit-' tle effect onthe overall heating action of the stove.

:It is preferred to provide the wall of the burner with a centrally located duct which delivers oxygen orair to the fuel spray issuingfrorn' the supply pipe so that the spray may be mixed with oxygen prior to entering the combustion chamber.

The novel features which are considered as characteristicof the invention are set forthin particular in the appended claims. The improved blast furnace stove itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of a specific embodiment with reference to the accompanying drawings, in which:

FIG. 1 is a side elevational view of a blast furnace stove which is constructed in accordance with our invention, a portion of the checker chamber being broken away;

FIG. 2 is an enlarged vertical section through the combustion chamber and burner of the stove shown in FIG. 1, the section being taken in the direction of arrows as seen from the line IIII of FIG. 3;

FIG. 3 is a fragmentary horizontal section as seen in the direction of arrows from the line III-III of FIG. 2; FIG. 4 is a fragmentary horizontal section as seen in the direction of arrows from the line IVIV of FIG. 2;

and

FIG. 5 is a fragmentary vertical section as seen in the direction of arrows from the line V-V of FIG. 2.

Referring to FIG. 1, the blast furnace stove comprises a first upright tower 1 having a checker chamber 2 and a cupola or dome 3. The cupola is connected with a horizontal passage 4 leading to the cupola 5 of a second upright tower 6, hereinafter'called combustion chamber,

; which is mounted on a framework 7. The checkers in the chamber 2 are heated by products of combustion streaming from the tubular chamber 6 and cupola 5 through the passage 4, cupola 3 and downwardly through the tower 1 to be withdrawn through a chimney conduit 8 provided with a valve 8'. In the on wind stage, air is admitted through a cold air blast main 8a which is provided with a valve 8a, and such air is heated by flowing upwardly through the checker chamber 2, thereupon through the cupola 3, passage 4, cupola 5, chamber 6 and into a hot-air blast main 10 provided with a valve 10'. The lower end of the combustion chamber 6 is connected with a special burner 9 which is constructed, mounted and operated in accordance with the present invention.

As shown in FIG. 2, the burner 9 comprises a horizontal wall 11 which is provided with a series of vertical channels 12 and 13. The channels 12, 13 form an annulus (see FIG. 3) wherein the channels 12 alternate with channels 13. Furnace gas is admitted through channels 12, and the channels 13 serve to admit air or oxygen. FIG. 5 shows that the upper end of each channel 12 communicates with the upper end of the adjoining channel 13 so that such upper ends together define a mixing orifice 14 which discharges a mixture of furnace gas and oxygen-containing gas into the lower zone of the combustion chamber 6. The channels 12, 13 are separated by vertical ribs 46 of the wall 11, and FIG. 5

3 shows that the adjoining mixing orifices 14 are separated from each other by vertical ribs 48. The ribs 46 and 48 are staggered with reference to each other, as seen in the circumferential direction of the wall 11.

FIGS. 2 and 3 illustrative a vertical duct 16 which extends axially through the wall 11 and is surrounded by the annulus of channels 12, 13. This duct 16 receives with clearance the upper portion of a vertical fuel supply pipe 17 having a spray nozzle or atomizer nozzle 1711 at its upper end which is preferably located below the level of the mixing orifices 14. The nozzle 17a discharges into the lower zone of the combustion chamber 6 a mixture of gaseous or liquid fuel (enriched furnace gas or oil) with streams of compressed air. The lower end portion of the supply pipe 17 extends through the lowermost section 18 of the wall 11 and is connected to a pair of supply conduits 19, 20 which respectively admit fuel and steam or compressed air. The conduits 19, 20 are provided with suitable couplings 19a, 20a which may be disengaged when the operators desire to withdraw the pipe 17 downwardly. This pipe 17 may be replaced by two or more supply pipes each of which may be withdrawn or inserted independently of the other or others.

The wall 11 resembles a cylinder and consists of refractory or other suitable heat-resistant material. This wall is surrounded by a substantially spherical metallic mantle 21 which defines two annular compartments 22, 23 separated from each other by an annular partition 24 Which is located in a horizontal plane. The upper compartment 22 communicates with the intake ends 27 of the air channels 13 and with the discharge end of an air supply conduit 25. The lower compartment 23 is in communication with the intake ends 28 of the duct 16 and with the discharge end of a further air supply conduit 26. The intake ends 27 of the air channels 13 extend radially outwardly and terminate at the peripheral surface of the bottom wall 11. The intake ends 28 also extend radially outwardly and are located at a level below the partition 24. The lower portion of the mantle 21 accommodates a hollow cylindrical sleeve 31 which is telescoped onto the wall 11 so that the parts 18, 21 and 31 define a third compartment 29 which communicates with the intake ends of the gas channels 12 and with the discharge end of a supply conduit 32 which delivers furnace gas. The mantle 21 supports a hollow vertical cylinder 30 which provides an airtight seal between the compartment 29 and duct 16. Thi cylinder 30 also serves to guide the fuel pipe 17. It will be noted that the intake ends of the channels 12 terminate at the underside of the Wall 11.

The rate at which air may enter the channels 13 can be regulated by adjustable valves 33 which are provided in the intake ends 27. Such valves may be adjusted through scalable openings 35 providedjgin the mantle 21 above the partition 24. Each opening "35 registers with one of the intake ends 27. Similar sealable openings 37 are provided in the mantle 21 below the partition 24 to facilitate adjustment of valves 40. which are mounted in the intake ends of the channels 12. The mantle 21 is provided with a third set of sealable openings 36 which register with the intake ends 28 of the duct 16, and such intake ends accommodate adjustable valves 34 which regulate the outflow of air from the lower compartment 23. As shown in FIG. 4, each intake end 28 has a diverging terminal portion 39 which is in direct communication with the vertical portion of the duct 16. Each terminal portion 39 accommodates an adjustable valve in the form of a vane or flap 38 which is pivotable about a vertical axis and serves to control the direction of the air stream which is admitted through the respective intake end 28. For example, the vanes 38 may be adjusted (through the openings 36) to form a twisting or spiralling column of air which rises in the shaft 16 and is intimately admixed to atomized fuel issuing from the spray nozzle 17a.

The operation of the stove is as follows:

In the on gas stage, the operators close the valves 8a, 10 and open the valve 8' so that the checker chamher 2 communicates with the chimney via conduit 8. The conduits 25, 26 respectively admit air into compartments 22, 23 and such air flows through the intake ends 27 of the channels 13 and through the intake ends 28 of the duct 16. The conduit 32 admits clean furnace gas into the compartment 29 whence the gas flows into the channels 12 to be mixed with air on passing through the orifices 14. The pipe 17 admits a mixture of fuel with steam or compressed air, and such mixture is atomized by the nozzle 17a which directs the resulting cone-shaped spray into the lower zone of the chamber 6 where the mixture is mixed with air admitted through the duct 16 and is then ignited in a well known manner, not forming part of our invention. The products of combustion rise in the chamber 6 to heat its walls and thereupon fiow through the cupola 5, passage 4, cupola 3, checker chamber 2, conduit 8 and on to the chimney, not shown. The gases entering the cupola 5 develop on combustion of furnace gases issuing from the orifices 14 and on combustion of atomized fuel issuing from the spray nozzle 17a.

A very important advantage of the improved burner is that eventual fluctuations in the heating value of furnace gases cannot affect or affect only slightly the heating of the checker chamber 2. This is due to the fact that the major part of heating action (for example, up to about 80 percent) is produced by combustion of fuel which is admitted through the pipe 17. Our invention is based on the recognition that the heating value of furnace gases is not sufficient to insure satisfactory heating of the blast which is admitted to a modern blast furnace.

In fact, even if the heating value of furnace gases is constant or nearly constant, we can still achieve substantial savings in coke by heating the checker chamber 2 to a very high temperature such as cannot be attained by heating with furnace gases alone. The burner 9 is comparatively simple and occupies little space. Also, the initial and maintenance cost of our stove is but a small fraction of the cost involved in the production and maintenance of conventional blast furnace stoves of which we are aware at this time.

As a rule, the pipe 17 will be connected to a source of oil or another liquid fuel; however, it is equally possible to utilize gaseous fuels with a high heating value. The air entering at 25 and 26 may but need not be preheated.

It will be understood that the fluid which enters the checker chamber 2 through the conduit 8a and leaves the combustion chamber 6 through the conduit 10 may be air, oxygen or preheated furnace gas.

Another very important advantage of our improved burner 9 is that the combustion of furnace gases and liquid or gaseous fuel is completed before the resulting hot products of combustion reach the passage 4. The flame which develops on ignition of atomized fuel issuing from the spray nozzle 17a is surrounded by a second flame which develops on ignition of the mixture issuing from the orifices 14. The temperature of the second flame is lower and this is of advantage because the material of the chamber 6 is less likely to develop fissures or other types of cracks. All such ingredients of atomized fuel which require more time for complete combustion will burn in the space surrounded by the second flame, and their combustion is invariably completed before the resulting products reach the cupola 5. Also, the second flame protects the wall structure of the combustion chamber 6 from flash flames which might developy on combustion of certain ingredients of atomized fuel and which could cause localized overheating of the combustion chamber. Complete combustion of furnace gases in the chamber 6 is insured by the provision of orifices 14 which cause such gases to mix intimately with oxygen or oxygencontaining air before the gases enter the combustion chamber. Thus, and even though the combustion of furnace gases is normally slow, such combustion is completed ahead of the cupola 5 which results in longer-lasting useful life of the heated parts of the improved blast furnace stove.

The operators will adjust the valves 33, 34 38 and/ or 40 whenever they find that the combustion of fuel and/or furnace gases does not proceed in the optimum manner. The valves 38 will spin the air streams entering the duct 16, and such spinning air streams will mix with atomized fuel to form a fuel-air mixture of exceptionally high homogeneousness.

The pipe 17 will be withdrawn for periodic inspection and/ or cleaning of the nozzle 17a. Also, and depending on the nature of fuel which is used in the burner 9, the pipe 17 may be replaced by one, two or more pipes of different diameters and/ or having different types of spray nozzles. The bore in the lower section 18 of the wall 11 is preferably dimensioned in such a Way that it may accommodate two or more fuel admitting pipes. This bore is sealed from the annular compartment 29 Whenever the cylinder 30 is in the position shown in FIG. 2. The wall 11 may but need not constitute a separable component part of the combustion chamber 6.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a blast furnace stove, in combination, an upright tubular combustion chamber having a lower end; and a burner comprising a wall of heat-resistant material provided at the lower end of said chamber, said wall having a substantially vertical oxygen-admitting duct provided with at least one radially outwardly extending intake end and an annulus of upwardly extending channels including oxygen-admitting channels which alternate with channels serving to admit furnace gases to said chamber, said duct comprising a vertical portion and said intake end having a terminal portion diverging forward and communicating with said vertical portion, adjustable valve means provided in said terminal portion and arranged to regulate the direction of oxygen flow from said intake end into the vertical portion of said duct, said channels surrounding said duct and said burner further comprising a substantially vertical pipe extending into said duct and arranged to admit into said chamber a fuel whose heating value exceeds the heating value of furnace gases, such fuel being mixed with oxygen which is admitted through said duct, a mantle of heat-resistant material surrounding said wall and defining therewith a compartment which communicates with said intake end, and means for admitting oxygen into said compartment.

2. A structure as set forth in claim 1, wherein said mantle is provided with a scalable opening to facilitate adjustment of said valve means.

3. A burner for the combustion chamber of a blast furnace stove, comprising a wall consisting of heat-resistant material and located at the lower end of the combustion chamber, said wall having an annulus of substantially vertical channels including air-admitting channels which alternate with channels arranged to admit furnace gases to the combustion chamber, said Wall further having a centrally located air admitting duct and said burner further comprising at least one substantially vertical tube extending upwardly into said duct and arranged to discharge into the combustion chamber a supply of finely distributed fuel whose heating value exceeds the heating value of furnace gases, such fuel and the air admitted through said duct forming a combustible mixture which is ignited in the combustion chamber together with the mixture of air and furnace gas issuing from said channels whereby the resulting products of combustion pass upwardly through the combustion chamber, said tube being provided with a spray nozzle at the upper end thereof to atomize the fuel prior to entry of such fuel into the combustion chamber, said channels having upper ends and the upper ends of said air-admitting channels communicating with the upper ends of adjoining gas-admitting channels to form orifices in which furnace gases are mixed with air prior to entering the combustion chamber.

4. A burner as defined in claim 3, wherein said wall has a peripheral surface and an underside, said air-admitting channels having radially outwardly extending intake ends which extend to said peripheral surface and said gas-admitting channels having intake ends which terminate at the underside of said wall, said burner further comprising a mantle surrounding said wall and defining therewith two separate compartments which respectively communicate with the intake ends of said air-admitting and gas-admitting channels, and separate conduit means for conveying air and furnace gases to the corresponding compartments.

References Cited by the Examiner UNITED STATES PATENTS 1,635,837 7/1927 Haag.

2,458,542 1/1949 Urquhart 158-11 2,851,093 9/1958 Zink et al. 158-11 3,007,512 11/1961 Te Nuyl et a1 158-11 3,124,110 3/1964 Buehl 126-363 X 3,150,865 9/1964 Goeke 263-19 3,236,279 2/1966 Beyer 158-11 3,244,220 4/1966 Kloecker 158-11 FREDERICK L. MATTESON, 111., Primary Examiner.

ROBERT A. DUA, Examiner. 

1. IN A BLAST FURNACE STOVE, IN COMBINATION, AN UPRIGHT TUBULAR COMBUSTION CHAMBER HAVING A LOWER END; AND A BURNER COMPRISING A WALL OF HEAT-RESISTANT MATERIAL PROVIDED AT THE LOWER END OF SAID CHAMBER, SAID WALL HAVING A SUBSTANTIALLY VERTICAL OXYGEN-ADMITTING DUCT PROVIDED WITH AT LEAST ONE RADIALLY OUTWARDLY EXTENDING INTAKE END AND AN ANNULUS OF UPWARDLY EXTENDING CHANNELS INCLUDING OXYGEN-ADMITTING CHANNELS WHICH ALTERNATE WITH CHANNELS SERVING TO ADMIT FURNACE GASES TO SAID CHAMBER, SAID DUCT COMPRISING A VERTICAL PORTION AND SAID INTAKE END HAVING A TERMINAL PORTION DIVERGING FORWARD AND COMMUNICATING WITH SAID VERTICAL PORTION, ADJUSTABLE VALVE MEANS PROVIDED IN SAID TERMINAL PORTION AND ARRANGED TO REGULATE THE DIRECTION OF OXYGEN FLOW FROM SAID INTAKE END INTO THE VERTICAL PORTION OF SAID DUCT, SAID CHANNELS SURROUNDING SAID DUCT AND SAID BURNER FURTHER COMPRISING A SUBSTANTIALLY VERTICAL PIPE EXTENDING INTO SAID DUCT AND ARRANGED TO ADMIT INTO SAID CHAMBER A FUEL WHOSE HEATING VALUE EXCEEDS THE HEATING VALUE OF FURNACE GASES, SUCH FUEL BEING MIXED WITH OXYGEN WHICH IS ADMITTED THROUGH SAID DUCT, A MANTLE OF HEAT-RESISTANT MATERIAL SURROUNDING SAID WALL AND DEFINING THEREWITH A COMPARTMENT WHICH COMMUNICATES WITH SAID INTAKE END, AND MEANS FOR ADMITTING OXYGEN INTO SAID COMPARTMENT. 